The present invention relates to an apparatus for manufacturing thin foil made of an Nixe2x80x94Fe alloy as a soft magnetic material, and more particularly to an apparatus for manufacturing a continued (i.e., continuous) Nixe2x80x94Fe alloy thin foil using an electrodeposition process.
Permalloy is a commercially-available Nixe2x80x94Fe alloy usable as a soft magnetic material. As well known, permalloy exhibits a high magnetic permeability and a low core loss, as compared to other soft magnetic material.
Conventionally, thin foils made of such an Nixe2x80x94Fe alloy are being manufactured using a method involving melting, casting, forging, and rolling processes.
U.S. Pat. No. 4,948,434 discloses the manufacture of thin foils having a thickness of 0.1 mm or less. In accordance with U.S. Pat. No. 4,948,434, a multi-stage rolling machine is used to conduct a cold rolling process and an annealing process in a multi-step fashion in order to fabricate thin foils having a thickness of 0.1 mm or less. This will now be described in more detail.
In accordance with U.S. Pat. No. 4,948,434, an Nixe2x80x94Fe alloy sheet is first prepared by hot-working a material essentially consisting of nickel from 76 to 81 wt %, molybdenum from 3 to 5 wt %, boron from 0.0015 to 0.0050 wt %, and the balance being iron and incidental impurities. The prepared Nixe2x80x94Fe alloy sheet is sequentially subjected to a primary cold rolling at a reduction ratio of from 50 to 98%, a primary annealing at a temperature ranging from 780xc2x0 C. to 950xc2x0 C., a secondary cold rolling at a reduction ratio of from 75 to 98%, and a secondary annealing at a temperature ranging from 950xc2x0 C. to 1,200xc2x0 C. Through such multi-step cold rolling and annealing processes, a thin foil having a thickness of 0.1 mm or less is manufactured.
However, the multi-step cold rolling process is complex and lengthy. Furthermore, this process has a difficulty in conducting it.
Meanwhile, U.S. Pat. Nos. 3,652,442 and 4,102,756 disclose an apparatus for electroplating of thin films which includes a stirring means for stirring an electrolyte in the form of a laminar flow in order to deposit, on a cathode plate made of a copper substrate, a metal this film having a uniform thickness and a uniform composition while having a uniform magnetic property. In accordance with the apparatus disclosed in U.S. Pat. Nos. 3,652,442 and 4,102,756, however, it is impossible to manufacture metal thin sheets in a continued fashion because the electrodeposition process used in the apparatus is intermittently conducted.
Therefore, an object of the invention is to provide a new method and apparatus which can be substituted for conventional methods involving a plurality of processes in the manufacture of permalloy thin foils.
Another object of the invention is to provide an apparatus for manufacturing a continued Nixe2x80x94Fe alloy thin foil having a uniform thickness using a single process.
Another object of the invention is to provide an apparatus for manufacturing a continued Nixe2x80x94Fe alloy thin foil exhibiting a magnetic anisotropy in a stirring direction of a paddle arranged between a cathode and an anode.
In order to accomplish these objects, the present invention provides an apparatus for manufacturing a continued Nixe2x80x94Fe alloy thin foil using an electrodeposition process.
In accordance with an aspect, the present invention provides an apparatus for manufacturing a continued Nixe2x80x94Fe alloy thin foil comprising: an electrolyzer adapted to receive an electrolyte containing, as a major component thereof, a solution of nickel and iron compounds; a cathode partially dipped in the electrolyte and arranged in such a fashion that it is rotatable; an anode completely dipped in the electrolyte and arranged in such a fashion that it faces the cathode while being spaced apart from the cathode by a desired distance; and a current device adapted to generate a flow of current between the cathode and the anode, whereby an Nixe2x80x94Fe alloy thin film is electrodeposited to a desired thickness over a surface of the cathode facing the anode, and then peeled off from the surface of the cathode, so that a continued Nixe2x80x94Fe alloy thin foil is manufactured.
In order to manufacture a continued Nixe2x80x94Fe alloy thin foil, the thin film electrodeposited over the cathode should be easily peeled off. To this end, the electrodeposition process should be conducted under appropriate conditions. In particular, the material and surface condition (surface roughness) of the cathode are important. If any one of the conditions associated with the electrodeposition process is inappropriate, it may then be difficult to peel off the Nixe2x80x94Fe alloy thin film electrodeposited over the surface of the cathode. Although the electrodeposited alloy thin film is peeled off, the resultant thin foil may be fragile. Otherwise, the thin foil may have a distorted shape. Consequently, it is impossible to obtain a desired Nixe2x80x94Fe alloy thin foil.
The material and surface condition (surface roughness) of the cathode have a direct influence on the bonding force of the Nixe2x80x94Fe alloy thin film electrodeposited over the surface of the cathode. In this regard, it is important to use a metallic material exhibiting a high corrosion resistance so that the cathode hardly reacts with an electrolyte used (that is, the cathode is hardly corroded by the electrolyte). It is also important for the cathode to have a surface being as smooth as possible.
To this end, the cathode is made of a metallic material exhibiting a high electrical conductivity and a high corrosion resistance to the electrolyte, for example, stainless steel such as steel of SUS 300 series (JIS standard), titanium, or titanium alloy. The surface of the cathode is also polished to have a surface roughness of 0.5 xcexcm or less, so that it is as clear as possible.
Also, a support roller, which is adapted to rotatably support the cathode, is preferably made of a non-conductive material exhibiting a high corrosion resistance in order to prevent it from reacting with the electrolyte while avoiding an electrodeposition thereon.
The cathode, which is rotatable, may have a drum shape or a belt shape. Where the cathode has a drum shape, the anode has an arc shape corresponding to the shape of the cathode. On the other hand, where the cathode has a belt shape, the anode has a planar shape.
A paddle, which serves to stir the electrolyte, may be arranged between the drum-shaped cathode and the anode. The paddle may have a configuration in which it pendulates in a circumferential direction of the cathode to stir the electrolyte. Alternatively, the paddle may have a configuration in which it reciprocates straightly in an axial direction of the cathode to stir the electrolyte.